For some, trials of captivity uncover the depth of `human spirit'. Former hostages and POWs say that while their experience never completely leaves them, it has altered outlook

Thirty-nine grateful Americans are now free from the hall of mirrors that is Beirut. They will not necessarily find the resumption of normal life easy. But their experience may well have revealed to them their own unexpected strength, say fellow former captives.

``It's like undergoing any situation of great stress. You get a new sense of what the human spirit is like,'' says Bruce Laingen, former charg'e d'affairs at the United States embassy in Iran.

On Nov. 4, 1979, as Mr. Laingen was leaving the Foreign Ministry in Tehran, some 3,000 demonstrators poured over the walls of the US Embassy compound. Cut off from his fellow diplomats, he returned to the ministry to seek help -- and remained trapped in the building for more than a year. Eventually, he was transferred and held with the other American hostages.

Today, Laingen remembers that he and most of his colleagues were pleased with how well they withstood the extraordinary pressure of their situation.

``Anyone is going to be surprised at how well you can cope,'' he says.

But coping doesn't mean it is easy to scoot through such an experience unchanged.

Moorhead C. Kennedy was the third-ranking diplomat at the US Embassy in Tehran at the time of the takeover. At one point, an Iranian student entered the room in which Mr. Kennedy was being held and asked him if he would like to write a letter. Kennedy says the thought flashed through his mind that he was about to be executed.

Because of these and other experiences as a hostage, he says, ``all the props got knocked away.''

He and his fellow prisoners felt that Foreign Service rank, economic status, and all the other indices by which they had measured themselves suddenly seemed far less relevant.

``You tend to pull everything together and determine what is and is not important,'' says Kennedy.

He left government service when he returned to the US and has since worked for organizations that try to promote international understanding.

Kennedy says his readjustment to normal life was not without difficulty. He talked too much at parties and had trouble sleeping.

Recently, with all the news-media attention on the crisis in Beirut, he has had hostage dreams again.

``It never completely leaves you,'' he says.

For the Americans held prisoner in Hanoi during the Vietnam war, conditions were far worse than they were for the hostages in Iran.

Beaten and often held in solitary confinement, US POWs were subjected to extraordinary physical and emotional stress.

Some cracked under the strain. Yet a Navy pilot named Everett Alvarez Jr., perhaps the longest-held POW, withstood this treatment to become the current deputy administrator of the Veterans Administration.

One former POW is a US senator; at least one other is a congressman.

``I am a far better person today because of the experience, though I certainly don't recommend the treatment,'' says Rep. John McCain (R) of Arizona, a former Navy flier, who spent six years in a North Vietnam prison.

Representative McCain says that being held as a POW affected different people in dramatically different ways. Basically, he says, whatever virtues or faults a person had were exaggerated by the intense pressures of captivity.

The experience restructured his ambitions, says McCain, leading him eventu-ally into politics. It also gave him an ``appreciation of weakness,'' he says -- of the problems and humiliations he had been insulated from by a middle-class upbringing.

What advice would all these former captives give the 39 former hostages from Beirut, who are now picking up the threads of their lives?

Enjoy the hoopla. It will never happen again, and it is reassuring to know you live in a country where millions of citizens have been hanging on your future, say all three former captives.

Don't take things too fast. Don't make too-sudden decisions about career or family. ``You're still a little spacey,'' Kennedy says.

Finally, talk. Get it out, get it behind you, and try to resume a normal life. ``Don't live it every day,'' Laingen says.

Both men are critical of press reports that the 39 returning hostages may be suffering from ``Stockholm Syndrome'' -- a tendency to sympathize with their captors' cause.

Just because the now ex-hostages have been saying they've learned of the complexities of politics in the Middle East, say Kennedy and Laingen, doesn't mean they've bought the story.